| HS Code | 992056 |
| Material | Polyamide 11 (PA11) |
| Form | Fine powder |
| Color | Grey |
| Density | 1.04 - 1.06 g/cm³ |
| Melting Point | 178 - 188 °C |
| Particle Size D50 | 28 - 35 µm |
| Bulk Density | 0.40 - 0.55 g/cm³ |
| Tensile Strength | 40 - 50 MPa |
| Elongation At Break | 250 - 320% |
| Shore D Hardness | 70 - 75 |
| Water Absorption At Saturation | ~1.2% |
| Maximum Continuous Service Temperature | ~100 °C |
| Chemical Resistance | Good resistance to oils, greases, fuels, and many solvents |
As an accredited Arkema Rilsan Fine Powders T GREY 7326 MAC PA11 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Supplied in 25 kg multi-layer paper bags, this PA11 fine powder is ready for electrostatic or fluidized bed coating applications. |
| Container Loading (20′ FCL) | Load 20′ FCL with Arkema Rilsan Fine Powders T GREY 7326 MAC PA11, palletized bags, secured, ventilated, dry, safe container loading. |
| Shipping | Shipped as Arkema Rilsan Fine Powders T GREY 7326 MAC PA11 — a polyamide-11 coating powder supplied in sealed multi-wall bags or fiber drums. Not classified as dangerous goods for standard freight, but must be kept dry, ventilated, and away from heat, sparks, and open flames to prevent dust ignition. Use covered, dry transport. |
| Storage | Store Arkema Rilsan Fine Powders T GREY 7326 MAC PA11 in its original, tightly sealed container in a cool, dry, well-ventilated area. Keep away from heat, open flames, oxidizers, and direct sunlight. Prevent moisture accumulation and static discharge. Ensure good housekeeping to minimize dust. Use within recommended shelf life. |
| Shelf Life | Shelf life is typically 2 years when stored sealed, cool, and dry in original packaging. |
Phosphated mild steel wirework for domestic dishwasher baskets represents one of the highest-volume downstream uses of Rilsan Fine Powders T Grey 7326 MAC PA11. The powder is applied after a seven-stage immersion pretreatment sequence consisting of alkaline degreasing at 55–65 °C, double counterflow rinse, iron phosphate conversion at 2.0–4.5 pH and 0.8–1.6 g/m² coating weight, and a final deionized rinse at conductivity below 30 µS/cm. Electrostatic spray application is run with a corona charging voltage of 60–80 kV, gun-to-target distance of 150–250 mm, and powder delivery air pressure between 0.8–1.5 bar. The target dry film thickness for domestic appliance wirework is 250–400 µm; coverage on inside corners of wire intersections is limited by Faraday cage effects, requiring oscillating gun motion and reduced voltage to 45–55 kV on second pass. Fusion is performed in a direct gas-fired convection oven at 220–240 °C for 8–15 min after substrate surface temperature reaches 210 °C. Typical rejection modes include phosphate sludge in recesses, outgassing pinholes from insufficient drying after rinse, and edge pullback when melt flow index is below 10 g/10 min at 215 °C/2.16 kg. Finished baskets are tested to ISO 9227 neutral salt spray for 1,000–1,500 h, ISO 2409 cross-cut adhesion with classification ≤1, and ISO 2813 specular gloss at 60° geometry between 50–70 GU depending on reclaim ratio. Virgin-to-reclaimed powder ratio is held at 80:20 on most appliance lines; above this ratio the proportion of fine particles alters transfer efficiency and surface flow. The PA11 chemistry provides resistance to alkaline dishwasher detergent at pH 10–12 and water at 70–85 °C, unlike epoxy powder grades that lose gloss and adhesion under prolonged wet alkaline exposure.
Stamped steel clips used in brake line and fuel line routing are coated by fluidised-bed immersion of preheated parts. The clips are loaded onto mesh conveyors and heated in a recirculating air furnace to 280–330 °C, then dipped into a fluidised bath of Rilsan Fine Powders T Grey 7326 MAC for 3–8 s. The powder particle size distribution, typically with a top cut near 125 µm for fine grades, influences fluidisation behaviour; moisture content above 0.25 wt% causes spitting and surface defects. Preheat temperature is not uniform across the clip cross-section: stamped edges lose heat more rapidly during transfer from furnace to dip tank, and residual heat determines fusion. Production lines therefore use infrared pyrometry to confirm that the metal surface remains above 230 °C at the point of entry into the fluidised bed. If the surface drops below 210 °C, partial fusion produces a sandpaper-like texture and low impact resistance. If preheat exceeds 340 °C, visible yellowing and viscosity rise occur in PA11. Coating thickness is controlled by the thermal mass of the substrate rather than immersion time alone; conventional practice yields 300–550 µm on the clip body and 150–250 µm on the sharp edges. Parts are then post-fused in an oven at 220–240 °C for 5–10 min. The coating must survive ASTM D638 tensile elongation greater than 20% when stripped, ISO 1519 mandrel bend without cracking, and SAE J400 gravelometer testing at -20 °C. A key processing conflict is that the fine powder grade retains electrostatic charge during fluidisation, causing clumping if relative humidity in the coating hall is below 35%. Reclaim blending is maintained below 25:75 virgin-to-reclaimed by weight to stabilise particle size distribution.
| Process variable | Observed production window for grey PA11 fine powder | Defect mode outside window |
|---|---|---|
| Steel clip preheat furnace set point | 280–330 °C | Low adhesion below 210 °C; yellowing above 340 °C |
| Fluidised-bed immersion time | 3–8 s | Thin edge film below 150 µm if too short; heavy sags if too long |
| Post-fuse oven temperature | 220–240 °C | Incomplete melt below 210 °C; degradation above 260 °C |
| Coating hall relative humidity | 35–60% | Electrostatic clumping below 35%; moisture defects above 60% |
| Virgin-to-reclaimed powder ratio | 75:25 to 100:0 | Transfer efficiency loss above 25 wt% reclaim |
Cast iron and steel valve bodies for district heating and hydraulic systems receive a 400–700 µm PA11 lining by electrostatic spray or fluidised-bed dip. Before coating, the metal is grit-blasted to white metal with SA 2½ cleanliness and an angular profile of 50–75 µm Rz, followed by solvent wipe to remove residual oil. A prime coat may be omitted because PA11 fusion directly onto blast-cleaned steel produces pull-off adhesion values greater than 15 MPa in ISO 4624 tests. Coating of internal passages requires reduced voltage; at 30–50 kV the powder penetrates bores of 25–50 mm diameter but only up to a distance-to-diameter ratio of approximately 3:1. Beyond that, fluidised-bed dip is preferred. The powder is not cross-linked; process conditions are selected to achieve complete melt flow without thermal degradation, typically 240–250 °C for 10–15 min for castings of 5–15 kg. Reclaimed overspray should be sieved below 150 µm and blended with virgin powder at a ratio not exceeding 30:70 to avoid excessive fine particle load and moisture uptake. The resulting lining resists water-glycol mixtures up to 50% glycol at 80 °C, mineral oil at 100 °C, and short-term exposure to hydraulic phosphate ester fluids. Dimensional changes after moisture conditioning are less than 0.3%, and hardness remains above Shore D 70. Compliance for potable water contact is evaluated under BS 6920 or AS/NZS 4020 when required. The finished component is a lined valve or pump casing used in circulating loops where both corrosion protection and low-friction fluid contact are demanded.
Cast aluminium pump housings are coated with Rilsan Fine Powders T Grey 7326 MAC after a chromium-free conversion coating or light anodising step. Aluminium substrates cannot tolerate furnace preheat above 280 °C without strength loss in heat-sensitive alloys; therefore, the powder is applied electrostatically at 50–70 kV and fused at 200–220 °C for 12–20 min. This lower fusion window requires finer particle size distribution and low moisture content below 0.20 wt%, because otherwise orange peel and cratering become pronounced. Outgassing from die-cast porosity is managed by pre-baking the castings at 180–200 °C for 30–45 min before powder application; this step reduces pinhole counts from more than 10 per dm² to under 2 per dm² in many production lines. Coating thickness on impeller vanes is specified at 300–500 µm, while machined flange faces are masked with high-temperature tape. Adhesion on aluminium is tested using ISO 2409 cross-cut or ISO 4624 pull-off; values above 10 MPa are typical for blasted aluminium. Erosive wear resistance measured by ASTM D4060 Taber abraser with CS-17 wheels and 1 kg load shows weight loss under 25 mg/1,000 cycles for PA11, which is used where slurry-bearing water would damage epoxy linings. The maximum continuous service temperature in alkaline aqueous environments is limited to 70–80 °C; above this, hydrolysis at the coating-metal interface can reduce adhesion over several thousand hours of immersion. The powder is factory-formulated and must be used without addition of external pigments; dry blending with other powder grades is generally avoided, and where required the blending ratio is limited to ≤10 wt% of a compatible additive powder to avoid changing charge distribution. The final part is a pump housing or impeller used in water circulation, chemical dosing, or HVAC hydronic circuits.
On fabricated steel heat sinks and transformer cooling fins, powder coating eliminates solvent emissions from solvent-borne nylon lacquer lines. The switch requires re-profiling thermal input because a 1.5–2.0 mm steel wall reaches fusion temperature more slowly than thin sheet, but has lower post-fuse cooling rate. Preheat to 250–270 °C followed by fluidised-bed immersion for 5–10 s produces a 350–600 µm film with dielectric strength greater than 20 kV/mm under IEC 60243-1. The grey PA11 grade must be applied over a chromate-free zirconium conversion coating or thin epoxy primer when used on galvanised steel to avoid zinc soap formation and loss of adhesion after damp heat ageing. The powder formulation for this application is adjusted with heat stabilizers; PA11 without adequate stabilisation discolours after 300–500 h at 110 °C, while stabilised grades retain dielectric and colour stability for 2,000 h under IEC 60216 thermal endurance testing. Reclaim ratio is held below 25 wt% because recycled fines change the particle-size distribution and may reduce edge dielectric coverage. Salt fog resistance is tested at 1,000 h under ISO 9227, with no creepage from scribe exceeding 2 mm. The powder must be stored below 30 °C and 50% RH; otherwise moisture pickup increases fluidisation defects. The terminal component is a passive cooling fin assembly or heat sink installed in power distribution and transformer enclosures, where the coating provides electrical isolation and corrosion resistance on formed steel surfaces.
Mechanical protection of threaded fasteners and suspension spring coils requires a different set of dimensional tolerances. Fasteners are coated by preheating to 290–310 °C and short dip times of 2–4 s, yielding a 100–200 µm film that must not interfere with thread engagement. Because the powder is a thermoplastic and not a thermoset, thread chasing after coating is sometimes necessary; production lines using this grade often specify a thread allowance of 0.2–0.3 mm per side. Spring coils receive a 250–450 µm coating that must withstand coil-to-coil contact and stone impact without chipping. Coating-to-wire diameter ratio is held below 1:10 to avoid coil stacking and rubbing. Low-temperature impact resistance is measured by ASTM D2794 reverse impact at -20 °C, with crack-free results above 80 in-lb for correctly fused PA11. The coating also reduces coil spring corrosion fatigue; parts are subjected to salt spray with 1,000 h exposure followed by cyclic loading. The grey pigmentation contributes to UV opacity, but outdoor weathering of unpigmented PA11 can degrade gloss after 1,500–2,000 h in ISO 16474-3 QUV. For applications requiring longer UV stability, a topcoat is required. Published data for this specific grey variant under all load cases is limited; qualification on production line samples remains necessary. The final products are fasteners, coil springs, and small brackets used in automotive chassis and industrial equipment.
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Arkema Rilsan Fine Powders T GREY 7326 MAC PA11 is a castor oil–derived polyamide 11 (PA11) thermoplastic coating powder supplied in a controlled fine particle-size distribution for electrostatic spray and fluidised-bed dip application. The grade prefix T identifies the unplasticised Rilsan T fine-powder series; the GREY 7326 designation refers to the pigmented grey colour reference; and the MAC suffix denotes a grade-specific particle-size control variant within the Rilsan Fine Powders range. The base polymer is synthesised from 11-aminoundecanoic acid and is supplied as a high-molecular-weight semi-crystalline resin. Typical unfilled Rilsan T PA11 fine-powder grades exhibit a density of 1.04 g/cm³ according to ISO 1183-1 and a melting temperature of 186°C according to ISO 11357-3. Grade-specific values for melt flow rate, particle-size distribution, and pigmentation-related mechanical changes must be confirmed against the current Arkema technical data sheet because published data for this specific configuration is limited.
| Property | Test method | Typical value |
|---|---|---|
| Density | ISO 1183-1 | 1.04 g/cm³ |
| Melting temperature | ISO 11357-3 | 186°C |
| Water absorption at saturation | ISO 62 | 1.9 wt% |
| Tensile stress at yield | ISO 527-2 | 40 MPa |
| Tensile strain at break | ISO 527-2 | >200% |
| Charpy notched impact at 23°C | ISO 179-1/1eA | no break |
| Shore D hardness | ISO 868 | 74 |
These values are representative of unfilled PA11 coatings after melt fusion and are not minimum specifications. The MAC particle-size variant may shift the D50 between approximately 30 µm and 150 µm depending on whether the material is intended for electrostatic spray or fluidised-bed dipping. Exact particle-size distribution data, melt flow rate, and the influence of grey pigmentation must be obtained from the current manufacturer datasheet. The base resin is typically melt-compounded on twin-screw extruders with length-to-diameter ratios between 36:1 and 48:1 before cryogenic grinding to the controlled powder particle-size envelope.
Electrostatic spray deposition of PA11 powder is governed by the aerodynamic drag of the particle cloud and the charge-to-mass ratio developed in the corona or tribo gun. For fine-powder grades with D50 below 60 µm, corona charging at 60–90 kV produces transfer efficiencies above 60% on grounded steel panels in industrial booths; coarser fractions used in fluidised-bed dipping are less sensitive to electrostatic charge retention but produce thicker films. Moisture uptake is a critical process variable because PA11 absorbs up to 1.9 wt% water at saturation according to ISO 62. Powder stored or conveyed at relative humidity above 60% can exhibit charge decay times below the interval between gun charging and substrate impact, lowering wrap-around coverage on recessed geometries. Pre-drying at 80°C for 4 h and maintaining a powder feed hopper at 20–30°C with <30% relative humidity are common controls on production lines using corona guns. The grey pigment in T GREY 7326 contains inorganic and/or carbon-based colourants that alter surface resistivity compared with natural PA11; confirmation of charge acceptance should be made with a powder resistivity cell and a corona gun at 100 µA output current.
A fluidised-bed dip line for this material typically requires a preheat oven capable of raising carbon-steel parts to 250–320°C, a fluidising hopper with a porous plate and regulated compressed air at 10–30 m³/h per square metre of bed area, and a post-cure zone held above the 186°C melting temperature of PA11. When cold parts are dipped into the fluidised cloud, powder particles sinter on contact; the final coating thickness is controlled by dwell time, part heat capacity, and bed temperature. For pipe and valve bodies with wall thickness greater than 10 mm, heat-load compensation is required to avoid a cliff-edge in coating thickness below 250°C; below this substrate temperature, incomplete particle coalescence produces pinholes and low adhesion at the substrate-coating interface. Immersion dwell times of 2–10 s are common for film builds of 250–500 µm. Post-dip curing at 180–200°C for 5–10 min completes melt flow and levelling.
When fluidised-bed dip coating replaces electrostatic spray for thick-film parts, the selection of T GREY 7326 MAC PA11 is dictated by the need for a coating thickness above 250 µm in a single operation. Electrostatic spray lines with multiple passes can achieve similar thickness, but the powder application rate of a fluidised bed is higher for parts with large thermal mass. A comparison of the two processes on cast-iron pump housings shows that fluidised-bed dip coating produces a 350–500 µm film in one immersion, while electrostatic spray typically requires 2–3 passes with intermediate heating to reach the same thickness. The PA11 coating provides low water absorption and resistance to hydrocarbons, but the substrate must be grit-blasted to SA 2.5 according to ISO 8501-1 before preheating. Adhesion on steel without phosphate or primer relies on mechanical interlock; the failure mode under crosshatch testing according to ISO 2409 is generally cohesive within the coating rather than adhesive at the metal interface. For aluminium substrates, a chromate-free conversion coating improves corrosion creep resistance under salt spray according to ISO 9227.
Melt viscosity in the Rilsan T PA11 powder family is a controlling variable for edge coverage on stamped, laser-cut, or machined components. The unplasticised T series has a higher melt viscosity than plasticised Rilsan fine powders, which improves resistance to creep at elevated temperature but reduces flow into sharp corners. On edges with radius below 0.5 mm, coating thickness may fall to 30–50% of the adjacent flat-surface build, a behaviour observed in fluidised-bed coating of stamped steel brackets. The resulting pinhole risk is managed by increasing part preheat temperature toward the upper end of the 250–280°C window or by specifying a finer particle-size cut to increase packing density before sintering. Dry-blending with natural or black PA11 grades should not be performed without pilot-scale trials because colourant migration and changes in surface resistivity can create localised film-thickness non-uniformity. The MAC grade is intended to limit this variability through controlled particle-size distribution; however, published data for this specific configuration is limited.
The grey pigmentation in Rilsan T GREY 7326 is not merely an aesthetic variable; it alters the dielectric surface resistivity of the powder and the long-term colour stability of the fused coating. Inorganic pigments such as titanium dioxide and carbon black are typically used in grey PA11 powders, and their concentration can shift the powder’s surface resistivity from the 1013–1015 Ω range typical of natural PA11 to lower values, reducing charge decay time. This effect lowers back-corona and orange-peel formation in electrostatic spray applications, but it may reduce the wrap-around effect on complex geometries. Colour stability under accelerated weathering according to ISO 4892-2 should be verified for the specific grey shade; PA11 homopolymer without UV stabiliser will undergo photo-oxidative embrittlement after prolonged outdoor exposure. In practice, the T series is often top-coated when outdoor UV resistance is required. The grey grade is not intended for direct food contact unless the final coating and pigment system are evaluated under FDA 21 CFR 177.1500 and any applicable migration limits.
Differences from other coating powders are defined by the thermoplastic semi-crystalline structure of PA11. Compared with PA12 coating powders, PA11 exhibits a higher melting temperature of approximately 186°C versus 176°C and a density of 1.04 g/cm³ versus approximately 1.01 g/cm³. PA12 may show lower water absorption at saturation, but PA11 provides a recognised combination of impact resistance, abrasion resistance, and chemical resistance in mechanical and anti-corrosion applications. Compared with plasticised Rilsan grades, the unplasticised T series has higher hardness and lower melt flow, requiring higher preheat temperatures for complete levelling. Compared with epoxy or polyester thermoset powders, the PA11 powder requires no chemical curing reaction and can be re-melted; however, its surface hardness and solvent resistance may be lower than those of certain crosslinked epoxy systems. The choice of T GREY 7326 MAC over other Rilsan Fine Powders is therefore driven by the required coating thickness, the substrate thermal mass, and the colour-specific electrostatic charging behaviour.
Compliance for this product must be confirmed against the current safety data sheet and technical data sheet. The base PA11 resin is covered by FDA 21 CFR 177.1500 for nylon resins used in repeated food contact, but pigmented and particle-size-controlled commercial grades require end-use testing for migration and extractives. Under the European Union REACH Regulation (EC) No 1907/2006, the polymer and its monomer components are registered by Arkema; downstream users must verify any candidate-list substances in the specific pigment package. The product is not classified as hazardous under Regulation (EC) No 1272/2008 in the standard powder form, but dust-air mixtures should be treated as potential combustible dust. Storage is recommended in sealed containers at 20–30°C and <50% relative humidity to prevent moisture uptake and particle agglomeration. Shelf life from the date of manufacture is commonly 24 months when stored under these conditions; material older than 24 months should be re-tested for melt flow rate and moisture content before use.
| Standard or regulation | Scope | Application to T GREY 7326 MAC PA11 |
|---|---|---|
| FDA 21 CFR 177.1500 | Nylon resins for repeated food contact | Base PA11 resin; pigmented grade requires end-use evaluation |
| REACH (EC) No 1907/2006 | Registration, evaluation, authorisation | Arkema registration for PA11 monomer/polymer; confirm SVHC in pigment package |
| RoHS Directive 2011/65/EU | Hazardous substances in electrical and electronic equipment | No intentional addition of Pb, Hg, Cd, Cr(VI), PBB, PBDE |
| ISO 8501-1 | Surface cleanliness of steel substrates | Grit blasting to SA 2.5 before coating |
| ISO 2409 | Cross-cut test for adhesion | Coating adhesion after fusion |
| ISO 9227 | Salt spray corrosion testing | Corrosion creep assessment on coated parts |
On production lines, the most frequent deviations from expected performance occur when powder is introduced into the hopper without controlling moisture regain, when preheat temperature is allowed to drift below 250°C on high-speed lines, or when the fluidising air humidity is not conditioned. In these cases, the observed failure modes are micro-void formation, loss of edge coverage, and reduced adhesion on cold corners. Batch-to-batch consistency for the MAC designation should be verified by incoming inspection of particle-size distribution by laser diffraction according to ISO 13320 and moisture content by Karl Fischer titration according to ISO 15512. The use of reconditioned powder recovered from spray booths is possible, but the recovered fraction should be blended with virgin powder at no more than 20 wt% to limit contamination from substrate dust and degraded fines. For fluidised-bed operations, bed temperature should be monitored with a calibrated infrared pyrometer at the part surface because thermal mass differences between thin brackets and thick valve bodies produce different coating-thickness outcomes under identical oven settings.
